Predicting carbon diffusion in cementite from first principles

Océane Buggenhoudt (1) , Thomas Schuler (1) , Chu Chun Fu (1) , Jean-Luc Bechade (1)

1 SRMP - Service de recherches de métallurgie physique

Combining first principles calculations with recently-developed statistical physics tools, we determine carbon diffusion mechanisms and the resulting diffusion coeffcients in pure-Fe and weakly alloyed $M_3$C cementites. The predicted coefficients in Fe3C are in good agreement with experimental measurements of carburization rate in ferritic steels. In our proposed diffusion mechanisms, C migrates by jumps between interstitial sites rather than via the C Frenkel pair mechanism, as proposed by previous studies based on semi-empirical simulations. In the alloyed cementites, the C diffusion can be slowed down due to the presence of Mn solutes up to 500 K, while it is mostly unaffected by the addition of Mo or Cr solutes.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Océane Buggenhoudt, Thomas Schuler, Chu Chun Fu, Jean-Luc Bechade. Predicting carbon diffusion in cementite from first principles. Physical Review Materials, 2021, 5, pp.063401. ⟨10.1103/PhysRevMaterials.5.063401⟩. ⟨cea-03350631⟩